Cardboard and corrugated cardboard are well known in the art. Indeed, the first form of corrugated, or pleated, paper was patented in 1871 under U.S. Pat. No. 122,023 to Jones. This paper was soon to be improved upon under U.S. Pat. No. 150,588 to Long which issued in 1874. The patent to Long discloses a filler layer, which could be corrugated board, with liner sheets disposed on each side. This is essentially the corrugated cardboard that we know and use today.
With the advent of corrugated cardboard and the recognition of its associated strength, corrugated boxes and containers began replacing wooden crates and the like in the early part of the 20th century, and such use continues in the packaging industry today. Corrugated cardboard is manufactured today using high-precision machinery lines, appropriately called “corrugators,” that can run at production speeds of 500 linear feet per minute, or even faster. The corrugated medium arrives at the corrugator on large rolls, is heated, moistened and formed into a fluted pattern on meshing geared wheels. This is attached to a first flat facing of liner-board with an adhesive to form “single face” board. A second flat facing of liner-board is similarly attached to the other side of the fluted medium to form “single wall” corrugated board or “cardboard,” which is really a misnomer in that “cardboard” is a generic lay term used to refer to any heavy paper or pulp-based board. The flat facing of liner-board can be formed from any number and grades of paper or pulp-based board, including bleached white, colored or even pre-printed board. Additionally, “double wall” corrugated cardboard can be formed from three sheets of liner-board and two fluted mediums in between them and “triple wall” corrugated cardboard can be formed from four sheets of liner-board and three fluted mediums between them, and so on. The assembly and method of the present invention is not limited to any one type of such corrugated cardboard.
It is also well known in the art that old corrugated cardboard sheets and containers made from them are an excellent source of paper fibers for re-cycling purposes. Such sheets and containers can be re-pulped in large vats of water where extraneous materials are filtered out. The resulting paper pulp “slurry” can then be used to make new paper and cardboard products. Such re-cycling helps with the preservation and conservation of wood resources and even helps areas without sustainable wood resources to build paper and packaging industries locally. The paper and packaging industries are receiving increased attention today as manufacturers faced with environmental, health and regulatory issues continue to look more closely to renewable and sustainable resources to meet increased demands for production. The need to use wholly or partially re-cycled paper-based products will increase to meet those demands.
In the packaging industry, it is also known in the art that a plurality of adjacent sheets of corrugated cardboard can be glued or adhered together with some sort of adhesive to form a relatively strong and laminated support structure. That is, one layer of corrugated cardboard may be glued to the next layer, and so on, to form a “block” of corrugated cardboard material. The process of forming such blocks, however, is a very time consuming and relatively expensive process, primarily due to the amount of glue that must be used and the way in which the glue or other adhesive must be evenly applied. This process is time consuming because, following application of the glue that binds the layers together, the glue must also dry prior to use of the block of corrugated material. The added adhesives and glues that are used also makes the resulting product one that does not lend itself well to the process of re-cycling since the added adhesives and glues constitute contaminants that require even further filtering of the paper pulp slurry during the re-cycling process.
Accordingly, it is an object of the present invention to provide a corrugated cardboard assembly that allows a plurality of adjacent sheets of corrugated cardboard to form a corrugated block or similar structure without the need to use extra adhesives to glue the adjacent sheets together. It is another object of the present invention to provide the methodology for constructing such a structure whereby structural integrity is maintained.